Four Moons

Daily Archives: March 26, 2014

Four moons of Saturn at once! Click for larger. Credit: NASA/JPL-Caltech/Space Science Institute

We get to see four of Saturn;s moons in this Cassini image. NASA describes them below. They do not comment on one of more spectacular shots of the rings Cassini has taken; they show up better in the larger versions at the NASA website.

Two pairs of moons make a rare joint appearance. The F ring’s shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring (the thin faint ring furthest from Saturn). Meanwhile, farther from Saturn the co-orbital moons Janus (near the bottom) and Epimetheus (about a third of the way down from the top) also are captured.

Prometheus (53 miles, or 86 kilometers across) and Pandora (50 miles, or 81 kilometers across) sculpt the F ring through their gravitational influences. Janus (111 miles, or 179 kilometers across) and Epimetheus (70 miles, or 113 kilometers across) are famous for their orbital dance, swapping places about every four years. They are also responsible for gravitationally shaping the outer edge of the A ring into seven scallops.
This view looks toward the sunlit side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Oct. 11, 2013.

The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 47 degrees. Image scale is 47 miles (76 kilometers) per pixel.